a card (usually plastic) that assures a seller that the person using it has a satisfactory credit rating and that the issuer will see to it that the seller receives payment for the merchandise delivered
Similarly, in an ultracapacitor, when voltage is applied across the two metal plates (i.e. during charging), a charge still builds on the two electrodes—one positive, one negative.
同样，在超级电容中，当两块金属片被施以电压（即充电）后，电荷建立于两极，一极为正，一极为负。
2
And the charges in the plates are what causes the electric field between the plates. That is how you can get the relation between voltage and charge in these guys.
板材上的电荷，生成了薄片间的电场，这就是得到电势与电荷之间关系的方法。
3
Ash particles have a small electric charge, and are then trapped on one of the plates.